Process for producing a shark fin analog

ABSTRACT

A shark fin analog utilized as a food is produced by heating to dissolve a mixture of gelatin, alginic acid or na alginate or a mannan, and water to form a gelatin sol, extruding the sol through a spinneret onto a rotating roller which has a surface wetted with a coagulating solution of divalent or trivalent metal salt and functions to elongate and tear off pieces of the sol, each piece having the shape of a shark fin with a thin streamlined profile in cross section, and washing the pieces with water.

This application is a continuation of now abandoned application Ser. No.918,657, filed Oct. 14, 1986, which is a continuation of now abandonedapplication Ser. No. 814,180, filed Dec. 24, 1985, which is acontinuation of now abandoned application Ser. No. 571,529, filed Jan.17, 1984.

BACKGROUND OF THE INVENTION

This invention relates to a novel process and apparatus for producing ashark fin analog, i.e., a simulated food resembling a shark finprocessed as a food.

Processed shark fins or ray fins have been cherished as an elegant foodmaterial for Chinese cuisine dishes such as soup. Particularly, with therecent trend in diet variety in foods, especially in elegant Chinesedishes, is widely sought after. Accordingly, the demand for shark finsis gradually increasing.

Shark fins practically utilized as the materials for soup or otherdishes are processed products of muscle filaments existing betweencartilage and skin of fins of shark or ray, having lengths, which maydiffer slightly depending on whether the product is a dried product or afrozen product, ranging on an average from about 50 to 100 mm. As to thethickness, the thickest portion is in the range from about 1.4 to 1.6 mmon an average. Shark fins generally have slender streamlined profiles incross section, as shown in FIG. 3, with one end being thick and pointedat its tip, and other end extending slenderly as a tail. Of course, somefins are greater in size than those described above, and the fins withgreater sizes are traded as higher class products. Further, shark finshave lustrous gold color or silver color and are highly valued as Kinshi(golden wings) or Ginshi (silver wings).

In ordinary cooking, Kinshi, etc. are produced from natural fins ofshark or ray. A great number of process steps and much labor arerequired in production of these food products, such as repeated cyclesof cooking under mild heating for a long time, removing bones andimpurities, and immersing in water for several days. Also considerableexperience and skill is necessary for successful cooking. Furthermore,depending on the conditions during production, only products of markedlyinferior quality may sometimes be obtained. Thus, under the presentcircumstances, shark fins of high quality cannot be supplied in largeamounts at low cost.

In view of the state of the art as described above, we have thought ofproducing a shark fin analog of high quality from gelatin. As is wellknown in the art, natural shark fins comprise primarily collagen, ofwhich the amino acid composition is substantially equal to that of thecollagen obtained from bones, skins or binding tissues of animals whichare generally used as the starting materials for gelatin. On the otherhand, the gelatin obtained from animal tissue collagen is today suppliedand utilized widely as a product of stable quality at low cost in largeamounts. Therefore, if the gelatin can be used as the starting materialfor production of a shark fin analog, it will become possible to supplyfood materials having flavor, nutritional values and othercharacteristics comparable to those of natural products at low cost.

In the prior art, it has been known to treat fibers of gelatin obtainedby wet spinning of a neutral solution thereof with a hardening agent,followed by washing with water and drying, to produce an edible gelatin(Japanese Patent Publication No. 8615/1970). However, the edible gelatinprepared according to this method has proved to have a mouth-feel unlikethat of shark fins and not satisfactory as compared with shark fins fromnatural resources. For example, it has low strength and cannot be formedto have a streamlined profile, and fabrication thereof into a shapesimilar to natural shark fins was impossible even when the gelatinconcentration was decreased or increased. Besides, while sufficientresistance to hot water is necessary for use in a heated liquid such assoup, the edible gelatin obtained according to the prior art methodbecomes very soft when boiled in hot water, and even those subjectedonce to spinning fail to have a mouth-feel of shark fins. Further,because of the treatment with a hardening agent, the treated gelatinbecomes hardened to exhibit a dry and crumbling feeling. There was alsoa drawback in the manufacturing steps including the drying step, in thata considerable amount of energy was consumed. Thus, the edible fibrousgelatin obtained according to the process of the prior art as describedabove has no satisfactory quality as an alternate for naturally producedshark fins and therefore could not be used satisfactorily as an elegantfood material for Chinese dishes.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide aprocess and an apparatus for producing a shark fin analog by usinggelatin, which product has excellent quality comparable to that ofnatural processed shark fins, and which can be used satisfactorily as anelegant food material for Chinese dishes.

Thus, the present invention provides a process for producing a shark finanalog which comprises heating to dissolve a starting material mixturecomprising (a) gelatin, (b) alginic acid or an alginate or a mannan, and(c) water, further containing, if necessary, one or more protein such asegg white, casein, vegetable protein and collagen, spinning, theresultant gelatin sol into a coagulation bath comprising a solution of adivalent or trivalent metal salt thereby to form a structure of astreamlined profile in cross section (hereinafter referred to asstreamlined shape), washing the spun product with water, and removingwater from the washed product.

The present invention also provides an apparatus for producing a sharkfin analog, which apparatus comprises a spinning header and nozzle(hereinafter referred to as a spinneret) for discharging a gelatin soldissolved by heating, an elongating and tearing-off roller which rotatesunder the spinneret and receives and elongates the gelatin soldischarged from said spinneret to tear off the sol spun into astreamlined shape, and a coagulation bath for coagulating the gelatinsol spun into the streamlined shape.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1a and FIG. 1b are a plan view and a side elevational view,respectively, of an embodiment of the apparatus according to the presentinvention;

FIG. 2 is a schematic side elevation showing the state of the deviceshown in FIG. 1 during operation; and

FIG. 3 is a sectional view showing a natural shark fin.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, in the first place, in addition togelatin, alginic acid or an alginate or a mannan is added thereto andmixed together with water to provide a starting material mixture. By theaddition of these other substances to gelatin, the product obtained canbe made similar in both mouth-feel and appearance to natural shark fins.As the alginate, sodium alginate is preferable. As the mannan, not onlymannan in a narrow sense but also the mannan in a broad sense, includinggalactomannan, glucomannan and konjak-mannan, may be used.

The amounts of the respective components are preferably 5 to 50% for and1 to 10% for alginic acid, an alginate or a mannan, the balance beingwater, based on the weight of the starting material to which water hasbeen added. At a level of gelatin less than 5%, the product obtaineddoes not have the good mouth-feel is of shark fins and also poor inappearance. On the other hand, at a level higher than 50%, its spinningcharacteristic is lowered, and the mouth-feel becomes unsatisfactory.With the use of alginic acid, an alginate or a mannan in an amount lessthan 1%, no strong mouth-feel can be obtained, while an amount in excessof 10% will result in poor spinning characteristic and too strong andunfavorable mouth-feel.

Other than these components, it is also possible to add one or moreproteins, such as egg white, casein, vegetable proteins and collagen, ifdesired. Their amount ranges from 1 to 10%, preferably from 1 to 5%, andthe texture and the taste of the product can be improved by addition ofthese components. In any case, the mixture is mixed with addition ofwater at room temperature and left to stand for 1 to 2 hours to causethe materials to become swollen with water.

The starting material mixture containing gelatin thus obtained is thenheated to the components. The heating temperature may be the dissolvingtemperature for gelatin or higher but is preferably in the range from30° to 80° C. At a temperature lower than this range, the viscosity isincreased excessively to impair the spinning characteristic, while atemperature higher than this range may also bring about deterioration ofthe gelatin, whereby the spinning characteristic will be impaired. Forthe sake of the viscosity after heating and the strength of the fibresformed, a temperature around 50° C. is preferred.

When the starting material mixture is dissolved by heating in thismanner, or thereafter, it is preferable to perform degassing. Degassingwill provide a product higher in quality with respect to both mouth-feeland appearance as compared with that obtained without degassing. As themethod for degassing, degassing under reduced pressure may be conductedduring dissolution or natural degassing may be conducted with additionof a defoaming agent during dissolution.

The gelatin sol obtained by heating to dissolve amply, preferably withdegassing, is then extruded into a coagulating solution through aspinneret to be formed by spinning into a streamlined shape. Thespinneret may have an aperture of about 0.5 to 5.0 mm in diameter,preferably about 1.0 to 3.0 mm, corresponding to the thickness of sharkfin. As the coagulating solution, an aqueous solution of a divalent ortrivalent metal salt is used. The divalent or trivalent metal salt ispreferably a salt of calcium, magnesium, aluminum or iron. Among thesesalts, an aqueous solution of a salt of calcium or aluminum, forexample, calcium chloride, calcium hydroxide, or aluminum sulfate, ispreferable. While the concentration of the aqueous solution depends onthe salt employed, a concentration of the order of 1 to 10% ispreferred.

Various methods may be employed for discharging the gelatin sol througha spinneret into a coagulation bath to be formed by spinning into astreamlined shape, that is, a profile shape similar to that of naturalprocessed shark fins as shown in FIG. 3. For example, while thecoagulating solution is caused to flow at a constant speed of the orderof 50 to 100 m/min. through a trough, the gelatin sol is discharged outinto the stream. When the leading end of the fibrous gelatin sol formedcontacts the coagulating solution, the fibrous gelatin is torn off bythe flowing of the solution at a certain length and immersed as it is inthe solution for 3 to 5 minutes, whereby the gelatin coagulates and isformed in a streamlined shape pointed narrowly at both ends of itsprofile. The formed product is taken out, washed thoroughly with waterand freed of excess water, whereupon a shark fin analog is obtained.After washing with water, a calcium salt or an aluminum salt may befurther added for hardening of the gelatin fibers.

In the present invention, as another method for spinning and forming agelatin sol dissolved by heating into a streamlined shape, it ispossible to use a method in which the gelatin sol is discharged outthrough a spinneret onto a roller wetted on its surface with acoagulating solution and rotating at a constant speed, and is furtherimmersed in said solution. The present invention also provides anapparatus for practicing this method. In one example of such anapparatus as shown in FIGS. 1 and 2, a hopper 1 is used for feeding thedissolved gelatin sol 2 obtained by heating the starting materialmixture. The gelatin sol in the hopper 1 is delivered by a pump 3 to aspinneret 4. The spinneret 4 has one or more orifices of about 0.5 to5.0 mm, preferably about 1.0 to 3.0 mm in diameterr as mentioned above.

Below the spinneret 4, there is provided a coagulating forming apparatusdesignated as a whole by reference numeral 6. The apparatus has acoagulation bath tank 8 provided at the upper portion thereof and filledwith a coagulating solution 7. A pump 9 is provided at the lower part ofthe coagulation bath tank 8 for discharging and circulating thecoagulating solution 7.

Between the coagulation bath tank 8 and the spinneret 4, a roller 10having a certain diameter is rotatably supported and at its lower partis immersed in the coagulating solution 7. This roller 10 is rotated,via a belt 12 by a motor 11 provided below the coagulation bath tank 8and the roller 10 rotates at a constant speed of the order of 100 to 200rpm. A shower nozzle 13 with several orifices for spraying thecoagulating solution is also suspended above the coagulation bath tank 8so that the coagulating solution can be supplied by jetting through thenozzle 13 into the coagulation bath tank. In the example shown in thedrawing, a part of the coagulating solution may be fed through theshower nozzle 13 directly onto the roller 10. In this case, the roller10 is wetted on its surface with both the coagulating solution from theshower nozzle 13 and the coagulating solution in the coagulating bathtank 8. Of course, it is only required that the roller by amply wettedwith the solution from either source. That is to say, if the roller 10is positioned below the shower nozzle 13 so as to receive thecoagulating solution therefrom, the lower part of the roller need not beimmersed in the coagulating bath, and vice versa. Also, wetting of theroller 10 with the coagulating solution 7 is not necessarily required,provided that the material for the roller and other factors are sodevised as to impart a peel-off characteristic to the roller.

In the operation of the apparatus of the above described construction,the dissolved gelatin sol 2 obtained by heating is delivered by the pump3 from the hopper 1 to the spinneret 4 and is discharged through itsorifice 5 onto the roller 10 rotating below. The gelatin sol 2 thusdropped on the surface of the roller 10 wetted with the coagulatingsolution as shown in FIG. 2 is drawn and elongated by the roller 10rotating in the direction of the arrow and torn off at a certain length,whereby it is spun into a streamlined shape 14 with one end being thickand pointed at its leading tip, and the other end being slenderlyextended as a tail. Thus, the roller 10 functions as an elongating andtearing-off roller. The gelatin sol torn off and formed into thestreamlined shape falls into the coagulation bath 7 and is immersedtherein for 3 to 5 minutes to be coagulated and is thereafter taken outby a convenient means from the coagulation bath tank 8. The coagulatingsolution 7 is taken out from the bottom of the tank 8, delivered againto the coagulating solution shower nozzle 13, and jetted through thenozzle into the tank 8 and/or onto the roller 10, thus being used undercirculation. After the product is taken out, it is washed with water toobtain a shark fin analog. If necessary, the analog product may betreated with a hardening agent.

The product thus obtained has great strength and has a streamlinedshape, its shape and appearance as well as lustre resembling those ofnatural shark fins. It also has excellent hot water resistance, iscapable of maintaining its fibrous shape even when immersed in a hotliquid such as soup, and also has a good property of forming spunfibers. Of course, when eaten, it can give a mouth-feel and texture likethose of natural shark fins and therefore it can be amply used as amaterial for elegant Chinese cuisine. Also, the apparatus according tothe present invention is simple in structure and operation, and it wasfound to be effectively utilizable for elongating and tearing off thegelatin sol formed by spinning into a streamlined shape and coagulated.

In order to indicate more fully the nature and utility of thisinvention, the following Examples are set forth, it being understoodthat these Examples are presented as illustrative only and are notintended to limit the scope of the invention. Throughout these Examples,quantities expressed in parts are by weight.

EXAMPLE 1

With 20 parts of gelatin are mixed well 5 parts of sodium alginate, and75 parts of water are added to the resultant mixture. After swelling atroom temperature for 1 hour, the mixture was heated in a warm bath at60° C. to thoroughly dissolve the gelatin. This step was followed bydegassing under reduced pressure. The gelatin sol was discharged througha nozzle with an orifice of 1.5 mm into a trough through which a 5%calcium chloride solution was flowing. As soon as the leading tip of thegelatin fiber contacted the liquid surface, a certain length of thefiber was torn off by the flow of the liquid, to be formed into astreamlined gelatin fiber pointed thinly at both ends. The fiber wasimmersed as it was in the 5% calcium chloride solution for 3 to 5minutes to be coagulated and then washed thoroughly with water to obtaina shark fin analog. By varying the flow velocity of the solution, thenozzle orifice and the nozzle position (height from the liquid surface),products having desired properties such as thickness, length and cuttingstrength as shown in Table 1 can be obtained.

                  TABLE 1                                                         ______________________________________                                                        Properties of shark fin                                       Flow            analog product                                                speed of                Diameter                                              coagulat-       Nozzle  at the                                                ing     Nozzle  posi-   thick por-                                                                             *1     *2                                    solution                                                                              orifice tion    tion *1  Length Strength                              ______________________________________                                         50 m/min                                                                             1.5 mm  4 cm    1.4 mm   l00 mm 1180 g/g                              100     1.5     4       1.4       60    1160                                  ______________________________________                                         *1: Average value of 100 fibers                                               *2: Strength is shown in terms of the strength measured by sampling 1 g o     the shark fin analog product in a cell for measurement and cutting the        sample with a piano wire plunger of a rheometer.                         

This product was cooked in a soup. With a natural shark fin as control,trial eating by 25 panel members was carried out. The results were asshown in Table 2. The product of this invention, as compared with thenatural shark fin, exhibited no significant difference in mouth-feel,taste and appearance, at a statistical risk level of 5%.

                  TABLE 2                                                         ______________________________________                                                       Mouth-          Appear-                                                       feel   Taste    ance                                           ______________________________________                                        Members who rated the                                                                          13       13       11                                         natural product as                                                            better                                                                        Members who rated the                                                                          12       12       14                                         product of the inven-                                                         tion as better                                                                ______________________________________                                    

EXAMPLE 2

Thirty (30) parts of gelatin, 3 parts of mannan and 2 parts of milkcasein were mixed and allowed to swell with 65 parts of water, and theswollen mixture was dissolved by heating at 45° C. and thereafterdegassed. The resultant gelatin sol was discharged by means of theapparatus shown in FIG. 1 onto a roller rotating while being in contactwith a 1% calcium hydroxide solution through a nozzle with an orifice of2.0 mm. The gelatin fiber discharged through the nozzle was drawn by theroller simultaneously with contact with the roller and torn off whilebeing elongated, dropping into the coagulation bath of the 1% calciumhydroxide solution. The gelatin fiber thus obtained was of streamlinedshape with one end being thick and pointed at its tip, and the other endbeing slenderly extended as a tail. Depending on the rotating speed ofthe elongating roller, the nozzle orifice, the position of the nozzlerelative to the roller (the nozzle height from the roller contact face),products having desired thicknesses, lengths and cutting strengths asshown in Table 3 can be obtained.

                  TABLE 3                                                         ______________________________________                                                        Properties of shark fin                                       Rotating        analog product                                                speed of                Diameter                                              elongat-        Nozzle  at the                                                ing     Nozzle  posi-   thick por-                                                                             *1     *2                                    roller  orifice tion    tion *1  Length Strength                              ______________________________________                                        100 rpm 1.5 mm  4 cm    1.8 mm    90 mm  960 g/g                              200     2.0     4       1.8       65    1020                                  100     1.5     4       1.4       85     840                                  200     1.5     8       1.4      120     880                                  ______________________________________                                         *1: Average value of 100 fibers                                               *2: Strength is shown in terms of the strength measured by sampling 1 g o     the shark fin analog product in a cell for measurement and cutting the        sample with a piano wire plunger of a rheometer.                         

This product was cooked in a soup, with a natural shark fin as control.The results of trial eating by 25 panel members are shown in Table 4below. The product of this invention, as compared with the natural sharkfin, exhibited no significant difference in mouth-feel, taste andappearance, at a statistical risk level of 5%.

                  TABLE 4                                                         ______________________________________                                                       Mouth-          Appear-                                                       feel   Taste    ance                                           ______________________________________                                        Members who rated the                                                                          14       13       14                                         natural product as                                                            better                                                                        Members who rated the                                                                          11       12       11                                         product of the inven-                                                         tion as better                                                                ______________________________________                                    

EXAMPLE 3

Forty (40) part of gelatin and 8 parts of sodium alginate were mixedwell, and the mixture was allowed to swell with 52 parts of water atroom temperature for 2 hours and then heated in a warm bath at 80° C. toamply dissolve the mixture to prepare a dissolved gelatin sol. Thegelatin sol was discharged by means of the apparatus shown in FIG. 1through a nozzle with an orifice of 1.5 mm onto a roller rotating whilebeing contacted by a 3% aluminum sulfate solution. Following the sameprocedure as described in Example 2, a shark fin analog product wasobtained. The analog product obtained was subjected to the panel testsimilarly as in Examples 1 and 2. As the result, there was nosignificant difference between the product of this invention and thenatural product, at a statistical risk level of 5%.

What is claimed is:
 1. A process for producing a shark fin analog, whichcomprises heating a starting material mixture comprising (a) 5-50% ofgelatin, (b) 1-10% of alginic acid, an alginate or a mannan, and (c)water, based on the weight of the starting material mixture, to producea gelatin sol, extruding the gelatin sol through a spinneret having anorifice of approximately 0.5 to 5.0 mm in diameter, dropping theextruded sol onto a descending portion of a surface of a roller rotatingat a rotation speed of 100 to 200 rpm and wetted with a coagulatingsolution comprising a divalent or trivalent metal salt, thereby toelongate and tear off the sol under rotational action of said roller andform the sol into a piece of a streamlined profile in cross-section withone end being relatively thick and pointed at its leading tip and theother end being relatively slenderly extended as a tail, furtherimmersing the sol in the coagulating solution, and wasing the resultantproduct with water.
 2. A process according to claim 1, wherein thestarting material mixture further contains a protein in addition to thegelatin.
 3. A process according to claim 2, wherein the additionalprotein is one or more members selected from the group consisting of eggwhite, casein, vegetable proteins and collagen.
 4. A process accordingto claim 3, wherein the additional protein is contained in an amount of1 to 10% by weight of the starting material mixture.
 5. A processaccording to claim 2, wherein the additional protein is contained in anamount of 1 to 10% by weight of the starting material mixture.
 6. Aprocess according to claim 1, wherein the starting material mixture isheated at a temperature in the range from 30° to 80° C.
 7. A processaccording to claim 1, wherein the divalent or trivalent metal salt isone or more salts of metals selected from the group consisting ofcalcium, magnesium, aluminum and iron.
 8. A process according to claim1, wherein the divalent or trivalent metal salt is one or more membersselected from the group consisting of calcium chloride, calciumhydroxide and aluminum sulfate.
 9. A process according to claim 1,wherein the spinneret has an orifice of about 1.0 to 3.0 mm in diameter.